1. Technical Field
The present invention relates to display devices.
2. Related Art
The conventional display device has a refractive-index changing unit on the outer surface of the optical waveguide (optical fiber). The refractive-index changing unit sandwiches the optical waveguide so that it can apply an electric field to the optical waveguide while driving the display device. Thereupon, the optical waveguide at a region where the electric field is applied is changed in its refractive index by the Kerr effect, thus causing the light propagating in the interior to emit to the outside. This causes light emission on the light-emitting panel (see JP-A-59-148030, for example).
Meanwhile, there is a disclosure of a structure having a core in a supper-lattice structure made by alternately forming two kinds of thin films, e.g. of amorphous silicon (a-Si) and silicon nitride (a-Si), and a clad made by two transparent electrodes sandwiching the same. The refractive index of the core is changed by applying a voltage to the transparent electrodes, based on which the light propagating in the core can be emitted to the outside (see JP-A-1-185692, for example).
Here, in the display device described in JP-A-59-148030, the refractive-index changing unit is made by a coat film of nitroglycerin and formed over nearly the entire surface of the display region. However, because this structure has a single-structured refractive-index changing unit, for a display device having a plurality of optical waveguides there is difficulty in driving those at each of the optical waveguides. Meanwhile, the display device described in JP-A-1-185692 involves a problem in that the manufacturing cost is high because time and labor is required in forming a core supper-lattice structure. Consequently, such optical-waveguide type display devices, despite being old in technical history, have never been put into practical application or onto the market.
The present invention provides a display device having a plurality of optical waveguide units and is capable of driving those at each of the optical waveguide units.